Conventional overhead electrical power transmission line cables comprise a central wire core having wire strands twisted thereabout. These wires or strands may be made of copper, aluminum, or aluminum alloy. It is also possible to have composite cables having a steel wire core with the surrounding strands being made of aluminum or of aluminum alloy.
They suffer from drawbacks. Firstly, the length required for the strands that are twisted around the central core is greater than the length of the resulting cable. If the angle formed between the strands and the axis of the cable is written .alpha. and if the length of the cable as a whole is written l, then the total length of any one strand is l/(cos .alpha.) so the additional length, corresponding to an increase in cost per unit length of cable, is l[(1/cos .alpha.)-1]. Further, the alternating current carried by the cable generates magnetic flux and thus gives rise to magnetic losses in a central wire core made of steel.
Further, the outer surface of the conductor is not smooth and this gives rise to considerable turbulence in the flow of air around the cable, and thus to cable vibration.
An object of the present invention is to provide a cable for an overhead electrical power transmission line of reduced cost, having lower magnetic losses, which is less subject to vibration, and which is manufactured and laid simultaneously.